Your entire brain is memory—and your memory is who you are

Memory fascinates us. We’ve created a genre of literature we call memoir. We take our memories and toy with them until they form a coherent narrative, one that makes sense of our lives and allows us to live with things we might like to forget. We’re embarrassed when we have a “Rick Perry” moment and can’t retrieve from our brain something that should be on the tip of our tongue. We recall vividly a night from 10 years back but can’t remember what we discussed at last week’s staff meeting. And we know that our memories are not set in stone, and that we can be induced to “remember” events that never happened.

Neuroscience tells us that memories are patterns of synaptic connections among the billions of neurons in our brain. Where our memories are stored depends on what kind of memories they are. Is this phone number destined to be a short-term memory, staying in our brain just long enough to dial? Is this memory procedural, involving motor skills like tying a shoelace or strumming a guitar? Is it traumatic or emotional, requiring the services of the amygdala to process? Is it a semantic memory, the kind of fact that keeps us up at night while we cram for a test? The brain has a spot for each of them, but we still don’t know where all of our memories reside.

This issue of Yale Medicine is devoted to these notions of memory and different ways to understand them. We asked doctors who write for their perspectives on how and why we turn our memories into stories. Doctors tell us why Alzheimer disease, which erodes our memories, is one of the most feared disorders in the country.

As Oscar Wilde put it, “Memory is the diary we all carry about with us.”